Copiously detailed and illustrated review. Here Viticci sings the praises of one of my own favorite new features:

Now, whenever you follow a link, a web view will be opened and
confined to the tab it’s been launched from. If you open a link
from your timeline, you can switch to the Mentions tab and do
something else; if you open a link from a DM, you can go back to
the timeline and read tweets while the page is loading.

This change to the app’s navigation makes for an incredibly more
convenient workflow for people who, like me, deal with links every
day and found it cumbersome to be forced to wait for a page to
load, act on it, then close it. The “multitasking” experience
inside Tweetbot is much improved because of this change and, in
comparison, the old app’s way of handling web views looks silly
now. For me, this has been particularly handy when receiving DMs:
I get a lot of direct messages every day, and with Tweetbot 3 I’m
no longer forced to close a webpage I’m reading if I have to reply
to a DM immediately.